Dan is right that antiwar sentiment is what motivates a lot of the “Obamacans,” which doesn’t rule out that those antiwar voters also tend to be “moderates,” as Jim argues.  I would guess that one of the reasons why so many antiwar voters did end up backing McCain in the primaries was the “maverick” mystique that moderate Republicans seem to find so appealing, because McCain did run as the moderate Republican candidate in 2000 and, to a large extent, in 2008, and because most antiwar Republicans are probably moderates.  Because moderates could think of McCain as one of their own, and because many of them, especially in New Hampshire, had backed him against Bush, they could pretend or convince themselves that McCain really was the opposite of Bush, even though he and Bush have scarcely differed on that much of importance since 2002 or 2003.  If they could do that when Ron Paul was in the race, they can do the same thing in the fall. 

Where I think Jim may be pushing this too far is when he says, “For most of these moderates, however, Barr will remind them of the kind of Republican who made them feel alienated from their party in the first place — Southern, socially conservative, and pro-impeachment.”  But most of these moderate Republicans were not disgruntled in 2004 when many of them lined up behind Bush, and it was not Southernness or social conservatism, much less memories of impeachment, that alienated them later.  However, I do agree that Barr is not likely to lure many of these Republicans away, as these are the Republicans least likely to respond well to any sort of restrictionist message and they are also among the least likely to respond well to a fiercely small government message.  Depending on how much Barr emphasizes restrictionist arguments, it could be Barr’s record on immigration that ends up taking more votes away from McCain, while the moderate Republicans will continue to support their standard-bearer.  There is the potential for a scenario here, as Dan’s title suggests, in which Obama draws very little Republican support.  Besides former Paul voters, the best prospects for future Barr support are probably to be found among former Romney voters, many of whom were also anti-Bush and antiwar, but who also include a much larger number of restrictionists and some of whom are inclined to have a grudge against McCain.